Rigid Fork Question

New to rigids and feel kinda dumb asking this but am looking at a used White Brothers rigid fork for my wuss. I'm checking on the ac length but it came off a 29er. Is ac they only factor here or do they make 29er specific and 26er specific rigid forks? Will it work if the ac is right- looking for something around 44-45cm?

I am running the 445mm (close to 45cm) on my 26" w/ Race King 2.2's (height of these tires is closer to that of a 2.4) and I still have about 2+" of clearance on the front. I don't see that they have a 29er specific Rock Solid fork only that it is available in about 3 different lengths. I think I could come close to squeezing a 29" wheel in mine but I would need to make sure the tire height was low enough. Can you have the guy measure it?

The 445 will result in the feel of running a bike with an 80mm travel squish front. That is what I was taking off so I was very pleased to hop on the bike and have the steering feel the same but more responsive and lighter due to the lack of squish! Love it!

A-C measurement is indeed all that matters, dependent on frame design. For instance, I run a "29er" fork on my 26"-wheeled Vulture frame because that frame was designed to utilize a 5" travel sus fork. So any 26" rigid fork would be too short. So let your frame design parameters dictate your fork length, not wheel size.